Fig 1:

Fig. 1

Preoperative radiograph of the left hip joint. A was the anteroposterior radiograph; B was the 45°Dunn radiograph; the bone hump in the left femoral head and neck region was flattened, and the bone was slightly sclerosis. Figure A measured LCE Angle is 32°; The measured α Angle in Figure B is 63° The black dots indicate the range of the cyst.

Fig 2:

Fig. 2

Preoperative CT of the left hip joint. A: the axial view; B shows the coronal view. Multiple cystic shadows can be seen in the left femoral head-neck area, and local bony uplift and sclerosis can be seen. The white arrow indicates the location of the cyst.

Fig 3:

Fig. 3

Preoperative MRI T2 scan of the left hip joint. A: the coronal view; B:the axial view. The anterior edge of the femoral head and neck junction can be seen with bony eminence, multiple cystic shadow locally, and the signal of the anterior superior labrum is increased. The white arrow indicates the femoral head-neck cyst and the asterisk indicates the labrum injury.

Fig 4:

Fig. 4

Intraoperative arthroscopic view. A:Explore cyst; B: debridement of cyst wall.

Fig 5:

Fig. 5

Postoperative radiograph of the left hip joint. A: anteroposterior radiographs; B: 45° Dunn radiograph; C: 45-day postoperative anteroposterior radiograph. The bone at the femoral head-neck was resected and the Cam deformity disappeared. Figure A measured LCEa is 32°; Figure B measured the α Angle of 44°; The LCEa measured in Figure C is 32°

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Abstract

In recent years, with the development of imaging and arthroscopy techniques, and a deep understanding of the pathogenic mechanism of femoroacetabular impingement syndrome (FAI), more and more scholars have gained a greater knowledge of the diagnosis and treatment of the disease. FAI not only has abnormal bone structure, such as cam deformity at the femoral head-neck junction, acetabular osteophyte formation, and bone cyst at the femoral or acetabulum, but also leads to the soft tissue injury of the hip joint, like acetabulum cartilage and labrum lesion, which might accelerate the progression of hip osteoarthritis. The incidence of bone cyst or synovial hernia at the femoral head-neck junction is not rare, which was seen as a sign of impingement. However, there is a paucity of literature about the treatment of bone cyst and the clear standard protocols of treatment, especially large or polycystic cysts. In this study, we reported a case of Cam FAI complicated with a giant bone cyst at the femoral head-neck junction and its characteristics and arthroscopic treatment. We also reviewed relevant documents and summarized the protocols of management of FAI complicated with femoral head-neck bone cyst for clinical reference.

Introduction

There are two types of FAI: Cam-type and Pincer-type. Classification of FAI is based on the anatomic characteristics of the pathology, specifically the femoral head-neck junction (cam lesion) or the acetabular rim (pincer lesion). Cam deformity is characterized by an abnormal/aspherical morphology of the proximal femur. Pincer deformity is characterized by focal or general over-coverage of the femoral head by the acetabulum. Abnormal morphology might produce contact stress when the hip joint moves, which may cause injuries of acetabulum cartilage, labrum, and femoral head-neck junction cartilage, eventually accelerate the progression of hip osteoarthritis [1x1Ganz, R., Parvizi, J., and Beck, M. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003; : 112–120

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]. For the treatment of FAI, arthrotomy surgery had gained satisfactory outcomes [x2Beck, M., Leunig, M., and Parvizi, J. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res. 2004; : 67–73

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,3]x3Beaule, P.E. and Le Duff MJZaragoza, E. Quality of life following femoral head-neck osteochondroplasty for femoroacetabular impingement. J Bone Joint Surg Am. 2007; 89: 773–779

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], but this management had the disadvantage of great trauma, such as more bleeding, and a long time for recovery. With the development of arthroscopic techniques in recent years, the minimally invasive treatment of FAI has achieved remarkable results [x4Ohlin, A., Ahlden, M., and Lindman, I. Good 5-year outcomes after arthroscopic treatment for femoroacetabular impingement syndrome. Knee Surg Sports Traumatol Arthrosc. 2020; 28: 1311–1316

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,5]x5Sansone, M., Ahlden, M., and Jonasson, P. Outcome after hip arthroscopy for femoroacetabular impingement in 289 patients with minimum 2-year follow-up. Scand J Med Sci Sports. 2017; 27: 230–235

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]. Arthroscopic treatment of FAI mainly involves the repair or reconstruction of the injured labrum and performs femoral osteoplasty or acetabuloplasty for femur or acetabulum respectively, to eliminate the factors causing impact. However, some studies have shown that postoperative residual impingement and extra-articular impingement are the main reasons for revision surgery [6x6Philippon, M.J., Schenker, M.L., and Briggs, K.K. Revision hip arthroscopy. Am J Sports Med. 2007; 35: 1918–1921

Crossref | PubMed | Scopus (294)
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, 7x7Gao, G., Zhang, X., and Xu, Y. Clinical outcomes and causes of arthroscopic hip revision surgery. Sci Rep. 2019; 9: 1230

Crossref | PubMed | Scopus (9)
| Google ScholarSee all References
, 8x8Gupta, A., Redmond, J.M., and Stake, C.E. Outcomes of Revision Hip Arthroscopy: 2-Year Clinical Follow-up. Arthroscopy. 2016; 32: 788–797

Abstract | Full Text | Full Text PDF | PubMed | Scopus (20)
| Google ScholarSee all References
, 9x9Newman, J.T., Briggs, K.K., and McNamara, S.C. Outcomes After Revision Hip Arthroscopic Surgery in Adolescent Patients Compared With a Matched Cohort Undergoing Primary Arthroscopic Surgery. Am J Sports Med. 2016; 44: 3063–3069

Crossref | PubMed | Scopus (16)
| Google ScholarSee all References
, 10x10Haefeli, P.C., Albers, C.E., and Steppacher, S.D. What Are the Risk Factors for Revision Surgery After Hip Arthroscopy for Femoroacetabular Impingement at 7-year Followup?. Clin Orthop Relat Res. 2017; 475: 1169–1177

Crossref | PubMed | Scopus (48)
| Google ScholarSee all References
]. In addition, FAI can also lead to the development of femoral head-neck cysts [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

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], but there are few reports on the surgical treatment of those bone cysts, and no uniform standard for the management of those cysts has been put forward. This case report retrospectively analyzed a case of Cam FAI combined with a giant femoral head-neck cyst (preoperative alpha angle 63°) and reviewed the relevant literature.

Case report

A 57-year-old man developed pain around the left hip 4 years ago after prolonged walking without apparent cause. The pain was dull and can be relieved after rest. There was no history of trauma. The symptoms lasted and began to worsen in nearly 1 year. The pain appeared after walking 100 m, mainly located in the groin area. Sports such as mountaineering and ball games were not possible. The physical examination showed mild limitation of passive flexion adduction and internal rotation and the FABER (Patrick) test was positive. Preoperative anteroposterior view radiograph and 45° Dunn view radiograph both showed flattening of the bone hump and slight sclerosis in the femoral head-neck region. The LCEa (lateral center-edge angle) was 32°(Fig. 1-A) and the α angle was 63°(Fig. 1-B). Preoperative Computed Tomography (CT) in cross-section and coronal slices not only showed multiple cystic shadows in the left femoral head-neck region, but also showed local bone uplift and sclerosis (Fig. 2). Preoperative Magnetic Resonance Imaging (MRI) in the coronal and axial scans of T2-weighted view showed bone eminence in the anterior margin of the femoral head-neck junction, multiple local cystic lesions with visible intervals, and increased signal in the anterosuperior labrum (Fig. 3). The preoperative modified Harris Hip Score (mHHS) was 63 points and the Visual Analogue Scale (VAS) was 7 points.

Fig 1: Opens large image

Fig. 1

Preoperative radiograph of the left hip joint. A was the anteroposterior radiograph; B was the 45°Dunn radiograph; the bone hump in the left femoral head and neck region was flattened, and the bone was slightly sclerosis. Figure A measured LCE Angle is 32°; The measured α Angle in Figure B is 63° The black dots indicate the range of the cyst.

Fig 2: Opens large image

Fig. 2

Preoperative CT of the left hip joint. A: the axial view; B shows the coronal view. Multiple cystic shadows can be seen in the left femoral head-neck area, and local bony uplift and sclerosis can be seen. The white arrow indicates the location of the cyst.

Fig 3: Opens large image

Fig. 3

Preoperative MRI T2 scan of the left hip joint. A: the coronal view; B:the axial view. The anterior edge of the femoral head and neck junction can be seen with bony eminence, multiple cystic shadow locally, and the signal of the anterior superior labrum is increased. The white arrow indicates the femoral head-neck cyst and the asterisk indicates the labrum injury.

Surgical procedure

The patient was placed in the supine position under lumbar anesthesia. The right hip joint was slightly pulled in the extension position to counter the traction force of the left hip joint. The final position of the left hip joint was under 10° flexion and 10° abduction, following mild adduction and internal rotation. The joint space was retracted under the lever action of the perineal column for about 60 min. Puncturing into joint space at 1 cm from the anterosuperior edge of the left greater trochanter (Anterolateral portal). The hip joint space was significantly enlarged and the puncture needle position was confirmed under intraoperative radiograph. The guide needle was inserted, and the blunt puncture instrument was inserted into the joint along the guide needle, finally inserted the trocar into the joint. The central compartment was confirmed by 70-degree arthroscopic lens observation. The guide needle was pierced under arthroscopic vision to establish the mid-anterior portal, then capsulotomy was performed. The exploration showed first-degree injury of femoral head-neck cartilage located in anterosuperior area with a size of about 25mm*10 mm, and first-degree injury of acetabulum cartilage located in anterosuperior area with a size of about 35mm*5 mm, which were treated with debridement treatment. Articular cartilage damage was assessed using the Outerbridge [12x12Outerbridge, R.E. The etiology of chondromalacia patellae. J Bone Joint Surg Br. 1961; 43-B: 752–757

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] classification system. Full-thickness longitudinal labrum tear can be seen in anterosuperior area. The torn labrum was sutured with six 3.0 mm absorbable suture anchors (Smith&Nephew 2.3) after the acetabular margin was freshened. The peripheral compartment was dealt after relaxing traction, radiofrequency was then used to expose Cam deformity range. Cam cyst lesion can be seen during femoroplasty. Cystic fluid flowed after the bone surface was completely removed (The color and viscosity were similar to synovial fluid and consistent with Gunther et al’ s findings [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

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]). The contents of the cyst were taken for pathology, and the cyst cavity was debrided with a burr. Multiple cysts were visible, with bone wall septum in the middle. The cyst septum was opened with a 4.5 mm round burr, the size of the cyst was about 35mm*20 mm and the depth was about 11 mm. Then we gently debrided the bottom of the cyst. Finally, grinding around the Cam deformity to complete the femoral osteochondroplasty. Endoscopic dynamic examination of impingement disappeared. The radiograph confirmed that the range of removal was satisfactory. Then sutured the capsule, irrigated the wound, closed the incisions, and bandaged the wound. The operation was completed.

Postoperative rehabilitation

After the operation, icing the affected hip joint for 24~48 h intermittently to relieve joint swelling and pain. NSAIDs were routinely administered to prevent heterotopic ossification for 3 weeks. Hip flexion and extension exercise and quadriceps muscle strength training were started 1 to 2 days after the operation. After 1 day, the patient could get down with the assistance of crutches, but the affected lower extremity avoided bearing weight. After 3 weeks, weight-bearing can be gradually walked, 6 weeks of full weight-bearing. Impact hip movement, such as jumping in place, was banned for 3 months.

Surgical outcome measurement

Postoperative anteroposterior pelvis radiograph shows the LCEa was 32°. Postoperative 45°Dunn view radiograph shows the αangle was 44°(19° Lower than preoperative status). The cam deformity and bone cyst were removed. Forty-five days after the operation, the patient's reexamination showed no special complaint. Physical examination showed passive flexion and internal rotation test and FABER (Patrick) test were negative. The anteroposterior radiograph showed LCEa was 32.0°. At three months follow-up time point, the mHHS score increased from 63 to 92, and the VAS scores improved from 7 to 2.

Discussion

At present, many studies have shown that hip morphology abnormality is a cause of hip osteoarthritis, including developmental hip dysplasia, borderline developmental dysplastic hip, and femoroacetabular impingement syndrome [x1Ganz, R., Parvizi, J., and Beck, M. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003; : 112–120

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]. Moreover, Leunig et al. reported that 4 in 26 (15%) FAI patients with femoral head-neck cyst had more than one cyst, and 25 in 26 patients had labral injury and 23 in 26 had cartilage injury [29x29Leunig, M., Mast, N.H., and Impellizerri, F.M. Arthroscopic appearance and treatment of impingement cysts at femoral head-neck junction. Arthroscopy. 2012; 28: 66–73

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]. Leunig et al. [28x28Leunig, M., Beck, M., and Kalhor, M. Fibrocystic changes at anterosuperior femoral neck: prevalence in hips with femoroacetabular impingement. Radiology. 2005; 236: 237–246

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] also found that most labrum injuries and cartilage injuries were in the anterosuperior part of the acetabulum. During the hip joint flexion, the femoral head-neck cyst contacts the acetabulum margin abnormally, leading to increased labrum stress and cartilage shear force. Thus, the author indicated that cysts were related to labrum and cartilage injuries.

As early as 1964, Angel [30x30Angel, J.L. The reaction area of the femoral neck. Clin Orthop Relat Res. 1964; 32: 130–142

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]called the cyst at the femoral head-neck junction a “reaction area”. Latter Pitt et al. [25x25Pitt, M.J., Graham, A.R., and Shipman, J.H. Herniation pit of the femoral neck. AJR Am J Roentgenol. 1982; 138: 1115–1121

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] described it in 1982 as “herniation pits” and suggested that the pressure caused by the strong iliofemoral ligament in the anterosuperior capsule during the hip full extension could lead to synovial tissue herniate into the femoral cortex through the bone defect, which was consisted with Landells's [31x31Landells, J.W. The bone cysts of osteoarthritis. J Bone Joint Surg Br. 1953; 35-B: 643–649

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] speculation. Furthermore, although Pitt [25x25Pitt, M.J., Graham, A.R., and Shipman, J.H. Herniation pit of the femoral neck. AJR Am J Roentgenol. 1982; 138: 1115–1121

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]and Daenen et al. [20x20Daenen, B., Preidler, K.W., and Padmanabhan, S. Symptomatic herniation pits of the femoral neck: anatomic and clinical study. AJR Am J Roentgenol. 1997; 168: 149–153

Crossref | PubMed
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] both found that the pathological change at this area was associated with femoral head-neck abnormality, neither of them attributed the origin of this cyst to underlying anatomical disorder. Leunig et al. [29x29Leunig, M., Mast, N.H., and Impellizerri, F.M. Arthroscopic appearance and treatment of impingement cysts at femoral head-neck junction. Arthroscopy. 2012; 28: 66–73

Abstract | Full Text | Full Text PDF | PubMed | Scopus (9)
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]named the cyst a “fibrous cyst” in 2005. In a comparison of 117 hip joints in patients with FAI and 132 hip joints in patients with hip dysplasia, he found 39 (33%) of the FAI group showed femoral head-neck cysts and no cyst in the hip dysplasia group, which might be attributed to repeated mechanical contact between femoral head-neck and acetabulum. Gunther et al. [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

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]had the same view as above, and reported a series of 3 cases of progressive enlargement of the femoral head-neck cyst, and believed that abnormal impingement might be the cause of progressive enlargement of the size of the cyst.

For the treatment of Cam FAI, femoral osteochondroplasty is mainly used to remove the non-spherical part of the femoral head-neck junction, which can improve the head-neck offset and create space for flexion and internal rotation to avoid impingement [1x1Ganz, R., Parvizi, J., and Beck, M. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003; : 112–120

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]. A comparative study by Buchler et al. [32x32Buchler, L., Neumann, M., and Schwab, J.M. Arthroscopic versus open cam resection in the treatment of femoroacetabular impingement. Arthroscopy. 2013; 29: 653–660

Abstract | Full Text | Full Text PDF | PubMed | Scopus (50)
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] showed that arthroscopic femoral osteochondroplasty for Cam FAI could achieve an anatomical shaping effect compared with opening surgery. For the treatment of FAI with femoral head-neck cyst, Gunther et al. [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

Crossref | PubMed | Scopus (22)
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]reported 3 cases of FAI complicated with large proximal femoral cysts and all underwent surgical decompression and bone grafting. In some cases, screws and plates are even used. And the author believed that if the cancellous bone defect is greater than 50% of the diameter of the femoral neck, internal fixation should be used, if the cortex is involved, even small lesions may require fixation [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

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]. In addition, fixation is sometimes necessary because osteochondroplasty may further weaken the strength of the femoral neck after cystectomy. Jamali et al. [33x33Jamali, A.A., Fritz, A.T., and Reddy, D. Minimally invasive bone grafting of cysts of the femoral head and acetabulum in femoroacetabular impingement: arthroscopic technique and case presentation. Arthroscopy. 2010; 26: 279–285

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] reported a case of FAI patient with a cyst in the femoral head-neck who underwent arthroscopic treatment and filled the cyst cavity with bone graft consisting of cancellous bone and demineralized bone matrix. Bone mineral density at the cyst recovered showed well 20 months after surgery. According to the results of Bonano's [34x34Bonano, J.C., Johannsen, A., and Mardones, R.M. The Effect of Resection Size in the Treatment of Cam-Type Femoroacetabular Impingement in the Typical Patient With Hip Arthroscopy: a Biomechanical Analysis. Am J Sports Med. 2020; 48: 2897–2902

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]study, the depth of Cam deformity resection of the anterolateral femur in FAI patients between 25 and 40% is safe in daily activities. Mardones et al. [35x35Mardones, R.M., Gonzalez, C., and Chen, Q. Surgical treatment of femoroacetabular impingement: evaluation of the effect of the size of the resection. Surgical technique. J Bone Joint Surg Am. 2006; 88: 84–91 (Suppl 1 Pt 1: p)

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]reported that 30% osteotomy in the anterolateral quadrant of the head-neck junction did not significantly change the capacity of carrying force loading of the proximal femur. For the treatment of the femoral head-neck cysts, we suggest that the smaller cysts can be directly abraded and the larger cysts should be debrided. In this study, we performed femoral osteochondroplasty for Cam FAI under hip arthroscopy by exploring and grinding the cyst wall to release cystic fluid, to remove the abnormal morphology at the femoral head-neck junction. Because the preoperative imaging of this case showed that the cyst was a part of the Cam deformity and the extent and depth of removal were appropriate, so no bone graft or fixation was performed in this case.

In addition, many researches indicate that residual impingement because of inadequate femoral osteochondroplasty is one of the most important risks for arthroscopy revision. Philippon et al. [6x6Philippon, M.J., Schenker, M.L., and Briggs, K.K. Revision hip arthroscopy. Am J Sports Med. 2007; 35: 1918–1921

Crossref | PubMed | Scopus (294)
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] reported 37 FAI patients with persistent pain after arthroscopy who eventually underwent revision surgery, 28 of whom underwent femoral osteochondroplasty during revision surgery. A study conducted by our institution [7x7Gao, G., Zhang, X., and Xu, Y. Clinical outcomes and causes of arthroscopic hip revision surgery. Sci Rep. 2019; 9: 1230

Crossref | PubMed | Scopus (9)
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]reported residual Cam deformity in 18 of 22 FAI patients undergoing revision arthroscopy. Newman et al. [9x9Newman, J.T., Briggs, K.K., and McNamara, S.C. Outcomes After Revision Hip Arthroscopic Surgery in Adolescent Patients Compared With a Matched Cohort Undergoing Primary Arthroscopic Surgery. Am J Sports Med. 2016; 44: 3063–3069

Crossref | PubMed | Scopus (16)
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]reported 9 cases (21.4%) underwent revision due to the residual Cam deformity. This condition was can also be seen in Gupta's [8x8Gupta, A., Redmond, J.M., and Stake, C.E. Outcomes of Revision Hip Arthroscopy: 2-Year Clinical Follow-up. Arthroscopy. 2016; 32: 788–797

Abstract | Full Text | Full Text PDF | PubMed | Scopus (20)
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]study, which indicated 32 of 70 (45.7%) FAI patients had residual Cam deformity. Moreover, a study of patients after arthroscopy for 7 years conducted by Haefeli [10x10Haefeli, P.C., Albers, C.E., and Steppacher, S.D. What Are the Risk Factors for Revision Surgery After Hip Arthroscopy for Femoroacetabular Impingement at 7-year Followup?. Clin Orthop Relat Res. 2017; 475: 1169–1177

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] showed that residual Cam deformity is a significant risk for revision surgery. Thus, performing complete femoral osteochondroplasty in patient with Cam deformity is of great importance. Due to the large size of the Cam cyst in this study, a residual cavity formed after the treatment was very large and deep, which affected the judgment of the peripheral Cam deformity. Therefore, we suggest that for arthroscopic treatment of FAI patients complicated with Cam cyst, femoral osteochondroplasty should be performed before debridement of the cyst, to avoid residual Cam deformity and revision surgery.

Besides, both Gunther's [11x11Gunther, K.P., Hartmann, A., and Aikele, P. Large femoral-neck cysts in association with femoroacetabular impingement. A report of three cases. J Bone Joint Surg Am. 2007; 89: 863–870

Crossref | PubMed | Scopus (22)
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]and Jamali's [33x33Jamali, A.A., Fritz, A.T., and Reddy, D. Minimally invasive bone grafting of cysts of the femoral head and acetabulum in femoroacetabular impingement: arthroscopic technique and case presentation. Arthroscopy. 2010; 26: 279–285

Abstract | Full Text | Full Text PDF | PubMed | Scopus (14)
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]studies did not specify changes in hip function scores in patients with FAI combined with femoral head-neck cysts before and after surgery. In our study, the mHHS score increased from 63 to 92 and the VAS improved from 7 to 2 after three months, indicating a significant improvement in hip function. Since there is only one case was reported in our study compared with the above-mentioned cases, more cases and medium or long-term follow-up period are needed to compare the clinical effect of different processing operations for FAI with Cam cyst.

Conclusion

FAI combined with femoral head-neck junction cyst is not uncommon, and studies have shown that cyst is associated with impingement, labral, and cartilage injury. Therefore, the femoral head-neck cyst might be a sign of the presence of FAI. As to the treatment of the cyst, different authors took fixation or bone grafting after cyst debridement. Based on our experience, we suggest that a small cyst can be abraded along with osteochondroplast and be seen as the standard of complete osteochondroplasty. For giant cyst, the main treatment is to clean up the cavity in an appropriate range, especially keep the bone of cyst bottom, as not to affect the mechanics of the femoral neck. In addition, femoral osteochondroplasty should be performed before cyst debridement, which can avoid affecting the judgment of Cam deformity and insufficient resection endoscopically. In general, for FAI patients with femoral head-neck junction cyst, arthroscopic treatment to repair injured tissue, remove impingement factor, and debride the cyst according to the size is a feasible and minimally invasive treatment approach with satisfactory short-term outcomes.

Author contribution

(I) Conception and design: Zhen-Xing Shao,Jian-Quan Wang

(II) Collection and assembly of data:Mamtimin Mahmut,Fan Yang

(III) Manuscript writing: Hao Sun

(IV) Spelling and grammar correction:Hong-Jie Huang, Xin-Zhang

(V) Final approval of manuscript: All authors

Disclaimer

none

Informed patient consent

The authors declare that informed patient consent was taken from all the patients.

The authors declare that informed patient consent was not provided for the following reason:

Fig. 4, Fig. 5

Fig 4: Opens large image

Fig. 4

Intraoperative arthroscopic view. A:Explore cyst; B: debridement of cyst wall.

Fig 5: Opens large image

Fig. 5

Postoperative radiograph of the left hip joint. A: anteroposterior radiographs; B: 45° Dunn radiograph; C: 45-day postoperative anteroposterior radiograph. The bone at the femoral head-neck was resected and the Cam deformity disappeared. Figure A measured LCEa is 32°; Figure B measured the α Angle of 44°; The LCEa measured in Figure C is 32°

Competing Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The full official funding agency name should be given:

National Natural Science Foundation of China (Grant Nos. 81871770)

National Natural Science Foundation of China (Grant Nos. 82072403)

Statement

This study was done with the consent of the authors institutional review board; IRB:Peking University Third Hospital Medical Science Research Ethics Committee; Study Number:M2019193

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#Hong-Jie Huang and Hao sun contributed equally to this paper as first authors
$Zhen-Xing Shao and Jian-Quan Wang contributed equally to this paper.

 

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